When two people talk to each other, they have to coordinate their activity. The speaker must use words in such a way that his listener will understand him. Part of this coordination is achieved through conventional word meanings and rules of combination, but a large part is achieved in other ways--by such "coordination devices" as salience, precedent, and explicit agreement. The proposed research is concerned with these alternative coordination devices and their role in comprehension. The research falls into four areas of language use. With definite reference, the aim is to discover how listeners identify the individuals that speakers are referring to when they say "the man over there," "my neighbor," or "the candle." With innovations, the aim is to discover how people understand newly coined expressions like "to porch a newspaper" or "to do a Napoleon for the photographer." With indirect speech acts, the aim is to characterize how people know when "This soup needs salt" is being used as a request, as a reprimand, as a promise, or as something else. And with ellipsis, aim is to discover how listeners use their knowledge of the context to grasp elliptical sentences like "In Palo Alto" (meaning, e.g., "I live in Palo Alto"). The overall aim of this research is to characterize how listeners infer what speakers mean from their knowledge not merely of context but also of the coordination devices speakers have available to them.